Container having internal strengthening ribs

ABSTRACT

A container includes internal strengthening ribs which increase the compressive strength of the container. The ribs have a rounded surface to facilitate manufacturing. In a preferred embodiment, the ribs are disposed on the inside surface of the container in spaced apart relationship.

TECHNICAL FIELD

[0001] The present invention pertains generally to plastic containers, and more particularly to a container which has internal ribs for strengthening the container.

BACKGROUND ART

[0002] Plastic (polymer) containers such as bottles are well known in the art. Often times such containers are fabricated using the blow molding process. It is advantageous for these containers to have a smooth exterior surface. Filling, labeling, and conveying equipment are all designed to handle smooth walled containers. If a container having exterior contours is to be filled, special equipment must be utilized. Also, labels are more easily applied to smooth walled bottles. In the case of vitamins and drugs, a smooth wall is desirable for the label because it must always be readable. If it were contoured, the label might be folded at a critical point making it unreadable. The FDA does not require smooth walled bottles, but it does require that the label be legible.

[0003] Because the exterior surface must be smooth, no external strengthening ribs or members may be utilized. This means that, in order to provide a container having a desired strength, the wall thickness of the container must be increased over and above that which would be required if external strengthening ribs could be employed. Such an increase in wall thickness is undesirable since more plastic must be utilized thereby increasing the cost of the container.

DISCLOSURE OF INVENTION

[0004] The present invention is directed to a container which is strengthened through the use of internal ribs. By using internal ribs, rather that external ribs, the external surface of the container is smooth and therefore receptive to the application of labels and the like. Because of the internal ribs, the wall thickness of the container may be reduced thereby lowering the cost of the container. Also, the cycle time for making each individual container is reduced because thinner walled containers cool faster than thicker walled containers.

[0005] In accordance with a preferred embodiment of the invention, a polymer container includes a hollow body having a top, an opposite bottom, a wall having an inside surface and a wall thickness, and a longitudinal axis passing though the top and the bottom. At least one rounded rib is disposed on the inside surface of the container for the purpose of increasing the compressive strength of the container.

[0006] In accordance with an aspect of the invention, the rib and the inside surface form first and second longitudinal concave junctions. When viewed in cross section, the junctions are rounded.

[0007] In accordance with another aspect of the invention, a plurality of ribs are disposed on the inside surface of the container in parallel spaced apart relationship.

[0008] In accordance with another aspect of the invention, the rib has height, wherein the height is between about 0.75 and 1.25 times the wall thickness of the container.

[0009] In accordance with another aspect of the invention, the ribs are oriented perpendicular to the longitudinal axis, parallel to the longitudinal axis, or form an acute angle with the longitudinal axis.

[0010] Other aspects of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF DRAWINGS

[0011]FIG. 1 is a side elevation of a container having internal ribs in accordance with the present invention;

[0012]FIG. 2 is a top plan view of the container;

[0013]FIG. 3 is a bottom plan view of the container;

[0014]FIG. 4 is a cross sectional view along the line 4-4 of FIG. 2;

[0015]FIG. 5 is an enlarged view of area 5 of FIG. 4;

[0016]FIG. 6 is a top plan view of a second embodiment of the container;

[0017]FIG. 7 is a cross sectional view along the line 7-7 of FIG. 6;

[0018]FIG. 8 is a cross sectional view of a third embodiment;

[0019]FIG. 9 is a cross sectional view of a fourth embodiment; and,

[0020]FIG. 10 is another enlarged view of area 5 of FIG. 4.

MODES FOR CARRYING OUT THE INVENTION

[0021] Referring initially to FIGS. 1 through 3, there are illustrated side elevation, top plan, and bottom plane views, respectively, of a polymer container having at least one internal strengthening rib in accordance with the present invention, generally designated as 20. Container 20 includes a hollow body 22 having a top 24, an opposite bottom 26, a wall 23 having a wall thickness T (refer also to FIG. 5) and an inside surface 28 (refer also to FIGS. 4 and 5), and a longitudinal axis 30 passing though top 24 and bottom 26. Container 20 can be of many shapes and sizes, such as that of the depicted bottle. Container 20 includes at least one rib 32 having a rounded surface 33 disposed on inside surface 28 (also refer to FIGS. 4 and 5). Rib 32 increases the compressive strength of container 20. That is, by utilizing rib 32, a larger squeezing force such as applied in directions 25 and 27 is required to deform container 20.

[0022]FIG. 4 is a cross sectional view along the line 4-4 of FIG. 2. It may be seen that rib 32 forms a closed structure which extends in ring like fashion around inside surface 28 substantially perpendicular to longitudinal axis 30 (also refer to FIGS. 2 and 3). In the shown embodiment, a plurality of closed ribs 32 reside in parallel spaced apart relationship around inside surface 28. In this fashion, the compressive strength of container 20 is increased along the entire height of the container.

[0023]FIG. 5 is an enlarged view of area 5 of FIG. 4, showing the structure of rib 32. Rib 32 comprises a rounded protuberance or bulge on inside surface 28 of container 20. Rib 32 and inside surface 28 form first 34 and second 36 longitudinal concave junctions. When viewed in cross section, junctions 34 and 36 are rounded. It is desired to have rib 32 and junctions 34 and 36 rounded so that during manufacture the inside surface 28 of container 20 will peel off of the core rod which is used to form the container 20 in a blow molding process. Sharp angles and corners make it more difficult to separate the inside surface 28 from the core rod.

[0024] Rib 32 has a height H. In a preferred embodiment of the invention, height H is between about 0.75 and 1.25 times wall thickness T. In many applications of the present invention, a height H of between about 0.020 inches and 0.040 inches has been found useful. Also, rib 32 has a width W. In applications of the present invention, a ratio of width W to height H of between about 4 and 8 to one has proven effective.

[0025]FIG. 6 is a top plan view of a second embodiment of the container 20, and FIG. 7 is a cross sectional view along the line 7-7 of FIG. 6. In this embodiment, a plurality of ribs 32 are disposed in parallel spaced apart relationship substantially parallel to longitudinal axis 30.

[0026]FIG. 8 is a cross sectional view of a third embodiment of the present invention. Rib 32 forms an acute angle A with a projection 40 of longitudinal axis 30 upon inside surface 28 of container 20. Rib 32 is disposed in helix like fashion on inside surface 28. In the shown embodiment, a plurality of parallel spaced apart ribs 32 are provided, each of which forms an acute angle A with projection 40 of longitudinal axis 30 upon inside surface 28.

[0027]FIG. 9 is a cross sectional view of a fourth embodiment of the present invention. In this embodiment, a second plurality of parallel spaced apart ribs 33 are provided in addition to the plurality of ribs 32 of FIG. 8. Each of the second plurality of spaced apart ribs 33 form an opposite acute angle-A with projection 40 of longitudinal axis 30 upon inside surface 28. The plurality of spaced-apart ribs 32 and the second plurality of spaced apart ribs 33 create a diamond shaped pattern.

[0028]FIG. 10 is another enlarged view of area 5 of FIG. 4. Rib 32 comprises a truss 35 which forms a ridged triangular framework (dashed) for supporting wall 23.

[0029] It may be appreciated that, in addition to the rib configurations shown herein, numerous other internal rib configurations and orientations may be utilized to strengthen container 20.

[0030] The container of the present invention can be fabricated from a variety of polymers, such as high density polyethylene, PET, polypropylene, PVC, and others.

[0031] The preferred embodiments of the invention described herein are exemplary and numerous modifications, variations, and rearrangements can be readily envisioned to achieve an equivalent result, all of which are intended to be embraced within the scope of the appended claims. 

I claim:
 1. A polymer container, comprising: a hollow body having a top, an opposite bottom, a wall having a thickness and an inside surface, and a longitudinal axis passing though said top and said bottom; at least one rib having a rounded surface disposed on said inside surface; and, said rib increasing the compressive strength of said container.
 2. A container according to claim 1, further including: said rib and said inside surface forming first and second longitudinal concave junctions; and, when viewed in cross section, said junctions being rounded.
 3. A container according to claim 1, further including: said rib having a height; and, said height being between about 0.75 and 1.25 times said wall thickness.
 4. A container according to claim 1, further including: said rib having a height; and, said height being between about 0.020 inches and 0.040 inches.
 5. A container according to claim 1, further including: said rib having a height and a width; and, a ratio of said width to said height being between about 4 and 8 to one.
 6. A container according to claim 1, further including: a plurality of said ribs disposed on said inside surface.
 7. A container according to claim 1, further including: said rib being closed and extending around said inside surface substantially perpendicular to said longitudinal axis.
 8. A container according to claim 7, further including: a plurality of said closed ribs residing in parallel spaced apart relationship around said inside surface.
 9. A container according to claim 1, further including: said rib disposed substantially parallel to said longitudinal axis.
 10. A container according to claim 9, further including: a plurality of said ribs residing in parallel spaced apart relationship.
 11. A container according to claim 1, further including: said rib forming an acute angle with a projection of said longitudinal axis upon said inside surface.
 12. A container according to claim 11, further including: a plurality of parallel spaced apart said ribs each of which forms an acute angle with said projection of said longitudinal axis upon said inside surface.
 13. A container according to claim 12, further including: a second plurality of parallel spaced apart said ribs each of which forms and opposite acute angle with said projection of said longitudinal axis upon said inside surface; and, said plurality and said second plurality of spaced apart ribs creating a diamond shaped pattern.
 14. A container according to claim 1, further including; said rib comprising a truss which forms a ridged framework for supporting said wall.
 15. A container according to claim 1, further including: said rib and said inside surface forming first and second longitudinal concave junctions; when viewed in cross section, said junctions being rounded; said rib having a height, said height being between about 0.75 and 1.25 times said wall thickness; said rib comprising a truss which forms a ridged framework for supporting said wall; a plurality of said ribs disposed on said inside surface; and, said plurality residing in parallel spaced apart relationship. 